Abstract
The Quarterly Journal of Microscopical Science for January, 1893, contains:—On the relationships and rôle of the Archoplasm during mitosis in the larval salamander, by John E. S. Moore (plate xxi.).—On the occurrence of embryonic fission in cyclostomatous polyzoa, by Sidney F. Harmer (plates xxii.–xxiv.). The extraordinary phenomena described in detail in this paper were announced in brief to the Cambridge Philosophical Society a couple of years ago. The completed investigations of the author indicate in the clearest way that the young larvæ of Crisia ramosa are produced as buds from an embryonic mass of cells found in the young ovicell. “At the end of segmentation the embryo consists of a small mass of undifferentiated cells, lying near the distal end of the follicle, which has increased largely in size, and now forms a spherical knob projecting freely into the interior of a spacious tentacle sheath;” after a time “the embryo, although remaining a solid mass without differentiation oF organs, grows out into several finger-shaped processes, which are generally directed towards distal end of the ovicell”… “these finger-shaped processes are divided up by a series of transverse costrictions into rounded masses of cells, each of which becomes a complete larva;” few rare cases in the Tunicates and Cœlenterata, where asexual reproduction of buds takes place from very feebly embryo forms are cited.—On two new genera and some new species of earthworms, by Frank E. Baddard, F. R. S.(plates xxv. and xxvi). Describes Trichochæta hesperidum, nov. gen. et spec. from Jamaica; Alvania millsoni, nov. gen. et spec. from Lagos; Polytoreutus magilensis, n. sp. from Magila, East Central Africa; and Pygmæodrilus lacuum, n. sp. from Lagos. There are also notes on Siphonogaster millsoni, F.E,B.—Observations on the gregarines of Holothurians, by E. A. Minchin, B. A. (plates xxvii. and xxviii.), These gregarines apparently first indicated by Kölliker, and identified by Schneider (1858), have since been studied by Cuénot, Mingazzini, Ludwig and Léger, and have now been closely investigated from fresh material found at Naples and Plymouth, by the author. Gregarina irregularis, n. sp. found on blood vessels of Holothuria, at Plymouth, is described; numerous details about the spores and sporozoites are given, and difficult question of the affinities of these forms is discussed.—A new Sporozoon in Amphioxus, by E C. Pollard (plate xxix.). These minute parasites were discovered in the epithehum ofthe intestine. Miss Pollard also figures a ciliate Protozoan found in the atrium of Amphioxus, which had been found some time back by Prof. Ray Lankester, he suggests that possibly the Sporozoon may be a stage in the life history of the ciliate form.—Studies on the Protochordata, by Arthur Willey. 1. On the origin of the branchial stigmata, præoral lobe, endostyle, atrial cavities, &c., in Ciona intestinalis, Linn., with remarks on Clavelina lepadiformis (plates xxx. and xxxi.). As the result of prolonged and very complete investigations, the author finds himself compelled to completely alter his previously published views as to the homologies existing between the various organs of the Ascidians and Amphioxus.
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Scientific Serials. Nature 47, 524–525 (1893). https://doi.org/10.1038/047524a0
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DOI: https://doi.org/10.1038/047524a0